While the original Mixup applies to both audio features and labels, our Mixup applies only to the features because we do not use labels.
In addition, as audio is log-scaled, we convert the input to a linear scale before the Mixup calculation and restore it to a log-scale again. In this paper, we refer to these operations as log-mixup-exp, from the analogy to the log-sum-exp[1]} calculation. Log-mixup-exp of \(i\) th input \(x_i\)  is
